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Tuesday, April 26, 2016

New Yorker on epigenetics

This is a fairly balanced account of recent progress in epigenetics (at least the part I excerpt below). But see here for negative reactions.

New Yorker: ... But, if epigenetic information can be transmitted through sperm and eggs, an organism would seem to have a direct conduit to the heritable features of its progeny. Such a system would act as a wormhole for evolution—a shortcut through the glum cycles of mutation and natural selection.

My visit with Allis had ended on a cautionary note. “Much about the transmission of epigenetic information across generations is unknown, and we should be careful before making up theories about the kind of information or memory that is transmitted,” he told me. By bypassing the traditional logic of genetics and evolution, epigenetics can arouse fantasies about warp-speeding heredity: you can make your children taller by straining your neck harder. Such myths abound and proliferate, often dangerously. A child’s autism, the result of genetic mutation, gets attributed to the emotional trauma of his great-grandparents. Mothers are being asked to minimize anxiety during their pregnancy, lest they taint their descendants with anxiety-ridden genes. Lamarck is being rehabilitated into the new Darwin.

These fantasies should invite skepticism. Environmental information can certainly be etched on the genome. But such epigenetic scratch marks are rarely, if ever, carried forward across generations. A man who loses a leg in an accident bears the imprint of that accident in his cells, wounds, and scars, but he does not bear children with shortened legs. A hundred and forty generations of circumcision have not made the procedure any shorter. ...